File: libtool.info,  Node: LT_CYGPATH,  Next: Cygwin to MinGW Cross,  Prev: Unix/Windows File Name Conversion,  Up: File name conversion

15.3.6.5 LT_CYGPATH
...................

For some cross-compile configurations (where the host platform is
Cygwin), the ‘cygpath’ program is used to convert file names from the
build platform notation to the Cygwin form (technically, this conversion
is from Windows notation to Cygwin notation; the conversion from the
build platform format to Windows notation is performed via other means).
However, because the ‘cygpath’ program is not (and should not be) in the
‘PATH’ on the build platform, ‘LT_CYGPATH’ must specify the full build
platform file name (that is, the full Unix or MSYS file name) of the
‘cygpath’ program.

   The reason ‘cygpath’ should not be in the build platform ‘PATH’ is
twofold: first, ‘cygpath’ is usually installed in the same directory as
many other Cygwin executables, such as ‘sed’, ‘cp’, etc.  If the build
platform environment had this directory in its ‘PATH’, then these Cygwin
versions of common Unix utilities might be used in preference to the
ones provided by the build platform itself, with deleterious effects.
Second, especially when Cygwin-1.7 or later is used, multiple Cygwin
installations can coexist within the same Windows instance.  Each
installation will have separate "mount tables" specified in
‘CYGROOT-N/etc/fstab’.  These “mount tables” control how that instance
of Cygwin will map Windows file names and paths to Cygwin form.  Each
installation's ‘cygpath’ utility automatically deduces the appropriate
‘/etc/fstab’ file.  Since each ‘CYGROOT-N/etc/fstab’ mount table may
specify different mappings, it matters what ‘cygpath’ is used.

   Note that ‘cygpath’ is a Cygwin application; to execute this tool
from Unix requires a working and properly configured Wine installation,
as well as enabling the GNU/Linux ‘binfmt’ extension.  Furthermore, the
Cygwin ‘setup.exe’ tool should have been used, via Wine, to properly
install Cygwin into the Wine file system (and registry).

   Unfortunately, Wine support for Cygwin is intermittent.  Recent
releases of Cygwin (1.7 and above) appear to require more Windows API
support than Wine provides (as of Wine version 1.2); most Cygwin
applications fail to execute.  This includes ‘cygpath’ itself.  Hence,
it is best _not_ to use the LT_CYGPATH machinery in libtool when
performing Unix to Cygwin cross-compiles.  Similarly, it is best _not_
to enable the GNU/Linux binfmt support in this configuration, because
while Wine will fail to execute the compiled Cygwin applications, it
will still exit with status zero.  This tends to confuse build systems
and test suites (including libtool's own testsuite, resulting in
spurious reported failures).  Wine support for the older Cygwin-1.5
series appears satisfactory, but the Cygwin team no longer supports
Cygwin-1.5.  It is hoped that Wine will eventually be improved such that
Cygwin-1.7 will again operate correctly under Wine.  Until then, libtool
will report warnings as described in *note File Name Conversion
Failure:: in these scenarios.

   However, ‘LT_CYGPATH’ is also used for the MSYS to Cygwin cross
compile scenario, and operates as expected.